Invert the precedence of | and when

Although this adds some drawbacks when it comes to typespecs,
it prepares us for when we have named patterns.
Remove :[] as a valid atom and do not allow remote container calls
Remove unecessary protocol in IEx.Autocomplete
Add a test to ensure no hanging in ParallelCompiler
Add missing fixture file for previous commit
Dict.Behaviour doc cleanup
Merge pull request #1988 from jwarwick/behaviour_doc

Dict.Behaviour doc cleanup
fix error with float midpoint rounding

- remove midpoint rounding option from Float.round/2
- always midpoint round away from 0
Merge pull request #1989 from chaslemley/fix_float_round_error

fix issue with Float.round/3 (midpoint_rounding)